The subject matter disclosed herein relates to a mobile or portable indoor mapping system, and in particular, to a system that can quickly and accurately generate three-dimensional coordinates of an indoor area.
The creation of three-dimensional (3D) computer models of existing structures has a number of uses in architecture, construction, archeology, and reconstruction applications. One method of generating the 3D computer model is using a laser scanner device. A laser scanner emits a beam of light and determines the 3D coordinates to a surface that reflects the light. The determination of the distance may be based on the time-of-flight of the light beam. Some laser scanner devices use a rotating mirror to reflect the light into the environment. The rotating mirror is rotated slowly about a second axis to obtain 3D coordinates in a spherical or semi-spherical area about the laser scanner.
Since the area typically being modeled may be large, multiple scans may need to be performed in order for all of the surfaces in the environment to be measured. The individual scans need to be registered to each other so that the acquired 3D coordinates may be defined in a common coordinate reference frame. To register the scans, the operator may place registration targets, typically reflective spherical targets, where the registration targets may be scanned from multiple locations. Since the targets are located in multiple scans, the operator may use these targets for registration.
Some systems have been developed with the laser scanner is places on a mobile system such as a cart. The laser scanner may then be rolled or otherwise carried about the area being scanned. To register the scans, the system may include inertial measurement units, such as gyroscopes and accelerometers to track the position where the scans are performed for purposes of registration. While the inertial measurement units will track the location of the system, these systems tend to drift as the mobile system is moved resulting in errors in the measurements. Further, these systems assume that the floor is level and the laser tracker maintains its alignment.
Accordingly, while existing indoor mapping systems are suitable for their intended purpose the need for improvement remains, particularly in providing an indoor mapping system that tracks the locations where scanning is performed without using artificial targets and with six-degrees of freedom.